1. Field of the Invention:
This invention relates to brake bleeder valve apparatus and a method for bleeding brakes utilizing the brake bleeder valve and, more particularly, to a brake bleeder valve having an integral check valve to prevent brake fluid and air from being sucked back into the brake system during a brake bleeding procedure when hydraulic pressure is removed from the system.
2. Description of the Prior Art:
For many years, the bleeding of brakes has been accomplished by bleeding one brake cylinder at a time. A brake bleeder valve is appropriately secured to each wheel cylinder. A hose or tubing is secured to the brake bleeder valve and the end of the tubing, remote from the brake bleeder valve, is disposed within a receptacle partially filled with brake fluid so that any fluid accidentally sucked back into the system when hydraulic pressure is removed from the system does not include air. Moreover, the presence of air bubbles flowing through the hydraulic fluid is easily noted by an observer.
After the hose and receptacle have been provided, the bleeding of the brakes becomes a job for at least two persons. One person is required to manually open the brake bleeder valve while a person inside the vehicle pushes against the brake pedal to apply hydraulic pressure to the brake system. When the brake pedal is completely pushed, the person at the wheel cylinder closes the valve to prevent fluid and, possibly, air from being sucked back into the system. After the valve is closed, the person inside the car then releases the brake pedal and fresh fluid from the brake reservoir flows into the system. Obviously, at some point, after typically two or three actuations of the brake pedal, additional hydraulic fluid will have to be added to the brake master cylinder reservoir. This may require a third person. In the alternative, either the person in the car or the person at the wheel cylinder may add the hydraulic fluid.
The bleeding of the wheel cylinder continues until no air bubbles are seen at the reservoir receptacle coming from the hose. At such time as the bleeding of one brake cylinder is completed, the brake bleeder valve is securely closed, the hose or tubing is removed, and the person moves to the next wheel cylinder where the process is repeated. Typically, the first brake cylinder bled is the cylinder farthest from the brake master cylinder. The next brake cylinder bled is the next farthest from the brake master cylinder, etc. For a vehicle with four wheels, one of the rear wheels is done first, then the opposite rear wheel. Then the front wheel farthest from the brake master cylinder and then the front wheel closest to the brake master cylinder.
Obviously, such brake bleeding procedure is relatively time consuming since two people are involved. There is equipment available which automatically keeps the brake master cylinder full of fluid. That eliminates the need for a third person, or for one of the two other persons involved to have to also add the hydraulic fluid as the hydraulic fluid is used. However, it is still necessary for the brakes to be bled one wheel cylinder at a time, and for two persons to be involved, one person to pressurize the brake pedal and the other person to open and close the brake bleeder valve with each pumping of the brake pedal.
Some bleeder valves have been designed so that the bleeding becomes a one-person job. Such systems include U.S. Pat. Nos. 2,771,093 (Wilson), 3,050,080 (Paglano), and 3,913,619 (Aulner et al).
The '093 (Wilson) patent discloses a bleeder valve having a radially extending bore communicating with an axially extending bore. A valve seat is disposed in the axially extending bore, and a tapered valve element is spring loaded in the axially extending bore against the valve seat. The valve element also includes a conically tapered surface at one end of the valve which extends into the valve seat in the wheel cylinder. The valve must accordingly be moved outwardly to allow fluid flow to the radially extending bore.
The '080 (Pagano) patent discloses a bleeder valve having a pair of ball check elements disposed in an axial bore. A compression spring biases the ball elements. A radially extending port communicates with the axial bore, and fluid flows out of the port when the fluid has been pressurized sufficiently to move the element 25 off its seat. The other ball element serves only to close one end of the axial bore and provides a structure against which one end of the compression spring bears.
The '619 (Aulner et al) patent discloses a bleeder valve which includes a radial bore which communicates with an axially extending bore. A ball element is disposed in the axial bore and is biased on a valve seat in the axial bore by a compression spring. The compression spring is held in the bore by a roll pin disposed in the axial bore. A cap is disposed over a bulbless portion of the valve element, and the roll pin extends through the bulbless portion. A cap is in turn disposed over the bulb portion and comprises a sealing element to prevent dirt, debris, etc., from getting into the axial bore when the apparatus is not in use.
The valve element includes a tapered portion adjacent to the radial bore, similar to the corresponding tapered portion of the valve element in the '080 patent. The tapered portions of the valve elements of both the '080 and '619 patent seal against a valve seat in the wheel cylinder in which the apparatus is installed.
It will be noted that in all three of the patents discussed above, the valve body comprises a single element. Each of the valve elements includes a tapered portion which seats against a mating portion in the wheel cylinder to which the valve bodies are secured. Accordingly, if the valve body is rotated slightly, even inadvertently, as through vibration, the braking system is liable to lose pressure and fluid. One embodiment of the apparatus of the present invention overcomes this specific problem by including a second valve member spring biased against an integral valve seat in the wheel cylinder. The valve element must be screwed a substantial distance before actuation of the brake system will develop sufficient pressure to overcome the bias of the spring to unseat the second valve element and thus to allow fluid to escape. Furthermore, bleeder ports in the secondary valve element remain covered by cylindrical walls of the main valve element for a substantial distance. Thus, a double security system is included to prevent the inadvertent loss of pressure and fluid in the brake system.
The apparatus of the present invention overcomes the problems of the prior art and allows all of the brakes to be bled at the same time, if desired. The apparatus of the present invention also makes it possible for one person to bleed all of the brakes by simply attaching a hose or tubing to each brake bleeder valve, providing receptacles to receive the hydrualic fluid from the brake system through the bleeder valves, and then opening the bleeder valves. With a check valve integral with the valve, no fluid flows until the brake system is pressurized, and when the pressure is removed from the system the check valve prevents fluid and air from being sucked back into the system.